JP2009194278A - Dielectric component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric component for restricting degradation of property of the dielectric component resulting from missing of atomic oxygen from dielectric. <P>SOLUTION: The dielectric component includes a substrate 1, a lower electrode 4, dielectric 6, a second adhesion layer 8 and an upper electrode 9. A diffusion prevention layer 7 is formed between the dielectric 6 and the second adhesion layer 8, and thereby the diffusion prevention layer 7 has stabilized property to the dielectric 6 in this constitution. As a result, missing of atomic oxygen of the dielectric is prevented, and an outstanding effect for preventing deterioration of the property is obtained in the dielectric component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to dielectric parts used for capacitors, various sensors, actuators and the like.

In general, in this type of dielectric component, a lower electrode made of Pt is formed on a substrate made of Si, and a dielectric made of PZT (lead zirconate titanate) is formed on the lower electrode. Further, an upper electrode made of Au is formed. In this configuration, in order to increase the adhesion between the substrate and the dielectric, a configuration in which a first adhesion layer made of Ti is formed between the two and the orientation direction of the dielectric crystals are made appropriate. For this purpose, a configuration is also known in which an orientation control layer made of PLT (lead lanthanum titanate) is formed between the first adhesion layer and the dielectric. And in order to improve the adhesiveness between a dielectric material and an upper electrode, the structure which forms the 2nd adhesion layer which consists of Ti between both is also known (refer patent document 1).
JP 2007-183147 A

  In the conventional dielectric component described in the above-mentioned patent document, oxygen of the oxide constituting the dielectric reacts with Ti constituting the second adhesion layer to form titanium oxide. Is lost, which changes the characteristics of the dielectric, leading to deterioration of the characteristics of the dielectric part.

  Hereinafter, this problem will be described in more detail. Generally, a dielectric component has a configuration in which a lower electrode is formed on the lower surface side of a dielectric and an upper electrode is formed on the upper surface side of the dielectric. Here, as the upper electrode, it is preferable to use a substance having high conductivity in order to reduce current loss at the electrode. For this reason, although a metal is normally used as the upper electrode, it is preferable to select a stable substance that is difficult to oxidize in order to prevent deterioration of the characteristics of the electrode due to oxidation. From such a viewpoint, Au has been used as the upper electrode. Au is a stable material that is extremely difficult to oxidize. However, if this Au is formed directly on the dielectric, the adhesion between the two is weak, and thus the upper electrode is liable to be peeled off from the dielectric. In order to solve this problem, a second adhesion layer made of a substance such as Ti having excellent adhesion to the dielectric and excellent adhesion to the upper electrode is formed between the dielectric and the adhesion layer. ing. Thereby, peeling of the upper electrode can be prevented.

  However, a substance that is required to have good properties for both the adhesion to the dielectric and the adhesion to the upper electrode, such as the substance used for the second adhesion layer, is a substance that easily reacts and oxidizes. There are many cases. The same is true for Ti used in the prior art. Such a second adhesion layer sometimes deprives the oxygen atom-containing dielectric of the oxygen atoms, and the substance forming the second adhesion layer may oxidize due to an oxidation reaction. As a result, the dielectric material in which oxygen atoms are deficient causes a phenomenon such as a defect in the crystal structure, resulting in a problem that the characteristics deteriorate.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a dielectric component capable of suppressing deterioration of characteristics of the dielectric component due to the deficiency of oxygen atoms from the dielectric. is there.

  In order to achieve the above object, the present invention has the following configuration.

  According to the first aspect of the present invention, there is provided a substrate, a lower electrode formed on the upper surface side of the substrate, a dielectric containing oxygen atoms formed on the upper surface side of the lower electrode, and the dielectric A diffusion prevention layer formed on the upper surface side of the diffusion prevention layer, and an upper electrode formed directly on the upper surface of the diffusion prevention layer or formed on the upper surface side of the intermediate layer directly formed on the upper surface of the diffusion prevention layer. The diffusion preventing layer is stable with respect to the dielectric. According to this configuration, since the diffusion preventing layer is stable with respect to the dielectric, it does not deprive oxygen atoms contained in the dielectric. As a result, the invention according to claim 1 has the effect of preventing oxygen atoms from being lost in the dielectric and preventing the deterioration of characteristics.

  In the invention described in claim 2, in particular, the diffusion preventing layer extends from the top surface of the dielectric to the side surface of the dielectric and the side surface of the lower electrode and extends to the substrate. The side surface of the dielectric layer is also covered with a diffusion prevention layer, so that even if the environment where the dielectric component is placed is a reducing atmosphere, oxygen atoms in the dielectric material are prevented from being lost, and the diffusion prevention layer is a second adhesion layer. Since the side surface of the layer is not covered, the second adhesion layer can deprive the atmosphere of oxygen, and by this oxidation, it does not deprive the oxygen atoms of the dielectric, and more stably oxygen atoms of the dielectric It is possible to prevent the loss of defects and to prevent the deterioration of characteristics.

  According to a third aspect of the present invention, the diffusion prevention layer is stable with respect to the upper electrode or intermediate layer directly formed on the upper surface thereof. According to this configuration, the diffusion prevention layer is directly formed on the upper surface. No dielectric reaction is caused by the formed upper electrode or the intermediate layer, so that the diffusion preventing layer can continue to maintain the property of being stable with respect to the dielectric, so that the dielectric is contained. Does not take away oxygen atoms As a result, the dielectric has the effect of preventing oxygen atoms from being lost and preventing the deterioration of characteristics.

  In the invention according to claim 4, in particular, the diffusion prevention layer is composed of an oxide, and according to this configuration, the diffusion prevention layer itself has already been oxidized and thus deprives oxygen atoms in the dielectric. Accordingly, this provides an effect that the loss of oxygen atoms constituting the dielectric can be prevented and the deterioration of characteristics can be prevented.

  In the invention according to claim 5, in particular, the diffusion prevention layer is made of nitride, and according to this structure, the diffusion prevention layer is formed of nitride which is a stable substance. The prevention layer does not deprive the oxygen atoms constituting the dielectric, thereby preventing the loss of oxygen atoms constituting the dielectric, and has the effect of preventing the deterioration of characteristics. .

In the invention described in claim 6, in particular, the diffusion prevention layer is made of one or more substances selected from SiO ₂ , SiN, SiON, BaTiO ₃ and SrTiO _3. Since the diffusion prevention layer is formed of a material stable to the body, the diffusion prevention layer does not take away oxygen atoms constituting the dielectric, thereby preventing the loss of oxygen atoms constituting the dielectric. It is possible to achieve the effect of preventing deterioration of characteristics.

  As described above, the dielectric component of the present invention forms a diffusion prevention layer on the top surface of the dielectric, and the diffusion prevention layer is stable with respect to the dielectric, so that the oxygen atom deficiency of the dielectric is reduced. Thus, it is possible to prevent the deterioration of the characteristics of the dielectric component.

(Embodiment 1)
In the following, the present invention, particularly claims 1 and 3 to 5, will be described with reference to the drawings.

  1 is a front sectional view of a dielectric component according to Embodiment 1 of the present invention.

In FIG. 1, a substrate 1 is a substrate made of Si. The shape of the substrate 1 may be an appropriate shape according to the use of the dielectric component. For example, when a dielectric component is used as an angular velocity sensor element that detects angular velocity, the shape of the dielectric component may be processed into a tuning fork shape. The insulating layer 2 is made of SiO ₂ formed on the substrate 1. The insulating layer 2 has a function of preventing charges generated in the lower electrode 4 described later from flowing into the substrate 1. The first adhesion layer 3 is formed on the insulating layer 2. The first adhesion layer 3 has a function for preventing the lower electrode 4 to be described later from peeling off, and the composition of the first adhesion layer 3 can be selected depending on the compatibility with the lower electrode 4. In the present embodiment, Ti is used as the composition. The lower electrode 4 is an electrode made of Pt formed on the insulating layer 2. The orientation control layer 5 is formed on the lower electrode 4 and has a function of making the crystal orientation of the dielectric 6 described later appropriate. As the orientation control layer 5, PLT, PLZT, or the like can be used. The dielectric 6 is a dielectric formed on the orientation control layer 5. The dielectric 6 is made of an oxide containing oxygen atoms, and for example, PZT can be used. The diffusion preventing layer 7 is formed on the dielectric 6 consists SiO _2, the diffusion preventing layer 7 has a function of preventing the diffusion of oxygen atoms of the dielectric 6 to another. The second adhesion layer 8 (intermediate layer) is formed on the diffusion preventing layer 7 and is intended to prevent peeling of the upper electrode 9 described later. The second adhesion layer 8 may be selected depending on the compatibility with the upper electrode 9, and Ti is used in the present embodiment. The upper electrode 9 is formed on the second adhesion layer 8 and is made of Au.

  A method for manufacturing a dielectric component according to Embodiment 1 of the present invention configured as described above will be described.

  As the substrate 1, a Si wafer can be used. An insulating layer 2 is formed on the upper surface of the substrate 1 by spin coating. In addition, as a formation method of the insulating layer 2, it can also form by oxidizing the surface of the board | substrate 1, and can also use thin film techniques, such as sputtering and CVD. The first adhesion layer 3, the lower electrode 4, the orientation control layer 5, the dielectric 6, the diffusion prevention layer 7, the second adhesion layer 8 and the upper electrode 9 can be formed by a thin film formation method such as sputtering or CVD. it can. In order to process into a shape according to the application, a method of performing etching after film formation by sputtering or the like can be used. A known manufacturing method can be used for these manufacturing methods. Moreover, it can manufacture without being restricted to said manufacturing method.

  In particular, the diffusion preventing layer 7 of the dielectric component according to the first embodiment of the present invention constructed and manufactured as described above will be described in detail. The diffusion preventing layer 7 has a function of preventing the oxygen atoms contained in the dielectric 6 from diffusing to the outside, and the diffusion preventing layer 7 is required to have a characteristic that does not deprive the oxygen atoms of the dielectric 6. That is, it is necessary that the force of the diffusion preventing layer 7 to bond with oxygen is weaker than the force of the dielectric 6 to keep oxygen atoms. In consideration of such conditions, there is an option of using an oxide as the diffusion preventing layer 7. This is because the oxygen atom of the dielectric 6 is not taken away if it is already oxidized and does not oxidize any more. There is also a method of using a very stable substance as the diffusion preventing layer 7.

  When attention is paid to the relationship with the second adhesion layer 8, it is preferable that the diffusion prevention layer 7 is a stable substance in the relationship with the second adhesion layer 8. This is because, for example, when an oxide is used as the diffusion preventing layer 7, if the oxygen atoms of the diffusion preventing layer 7 are deprived by the second adhesion layer 8, the diffusion preventing layer 7 deficient in oxygen atoms becomes a dielectric. This is because it may be considered that oxygen atoms are deprived from 6. From this point, the force that the diffusion preventing layer 7 keeps holding oxygen atoms is the force that the second adhesion layer 8 tries to bond with oxygen atoms. Stronger is preferred. Even if the diffusion prevention layer 7 is made of a substance that does not contain oxygen atoms, if the atoms contained in the diffusion prevention layer 7 react with the second adhesion layer 8, the diffusion prevention layer 7. The diffusion preventing layer 7 may deprive the oxygen atoms of the dielectric 6 due to the change of the properties of the dielectric 6, and therefore, the diffusion preventing layer 7 is a stable substance in relation to the second adhesion layer 8. Is preferable.

More specific description will be given below. SiO ₂ constituting the diffusion preventing layer 7 is an oxide and is not oxidized any more except under a special environment. Therefore, the diffusion preventing layer 7 does not take oxygen atoms in the dielectric 6, and oxygen vacancies in the dielectric 6 can be prevented from occurring. Of course, SiO ₂ is a stable material and is stable against PZT constituting the dielectric 6, not only depriving oxygen atoms of the dielectric 6, but also other chemistry with the dielectric 6. There is no reaction.

In addition, SiO ₂ is stable with respect to Ti constituting the second adhesion layer 8, and oxygen atoms of SiO ₂ constituting the diffusion prevention layer 7 are not deprived of Ti. There is no reaction in which oxygen is deprived from the constituent SiO ₂ and changed to Si, and the Si deprives oxygen atoms in the dielectric 6.

  In the above description, the term “stable” is used, which means that a chemical reaction does not occur in a normal atmosphere and a normal environment. That is, it means that a chemical reaction does not occur in the atmosphere under normal temperature and humidity conditions, and does not use the presence or absence of a chemical reaction in a special environment as a criterion for judgment.

In the above description, it is expressed that “no chemical reaction occurs”, but this does not include a microscopic chemical reaction in an equilibrium state. More specifically, there may be a case where SiO ₂ oxygen reacts with Ti microscopically at a certain moment, SiO ₂ changes to Si, and Ti changes to TiO _{2. 2} oxygen atom reacts with Si, TiO ₂ changes to Ti, Si also changes to SiO _2, and as a whole, the reaction that SiO ₂ changes to Si does not proceed, Such a case is not included in the chemical reaction described above.

In the present embodiment, SiO ₂ is used for the diffusion preventing layer 7, but the same effect is obtained even if SiON is used.

  In addition, when SiN is used for the diffusion prevention layer 7, since SiN is stable, atoms in the diffusion prevention layer 7 do not react with the second adhesion layer 8, and SiN is an oxide. However, since it is a stable substance, it does not deprive the dielectric 6 of oxygen atoms.

Further, BaTiO ₂ or SrTiO ₂ can be used for the diffusion preventing layer 7. These substances do not deprive oxygen atoms from PZT constituting the dielectric 6, and can prevent the dielectric 6 from being deficient in oxygen atoms. Furthermore, since these substances are also dielectrics 6, they may work more advantageous than the case where substances other than dielectrics are used for the diffusion prevention layer 7 in terms of dielectric constant.

Further, the diffusion preventing layer 7 may be made of two or more substances selected from the above-mentioned SiO ₂ , SiON, SiN, BaTiO ₂ and SrTiO ₂ .

  As described above, by preventing the diffusion preventing layer 7 from diffusing oxygen atoms in the dielectric 6, it is possible to prevent deterioration of the characteristics of the dielectric 6 due to diffusion of oxygen atoms.

  Note that the dielectric component in the first embodiment uses a material that is difficult to oxidize as the upper electrode 9, and thus has a configuration in which the second adhesion layer 8 with good adhesion is formed. In addition, the present invention can also be applied to the case where a substance that has good adhesion to the dielectric 6 but is easily oxidized is used. For example, the case where Ti is used as the upper electrode 9 is applicable. In this case, the upper electrode 9 can be formed directly on the upper surface of the diffusion preventing layer 7 without using the second adhesion layer 8. The diffusion prevention layer 7 at this time is preferably a stable material in relation to the upper electrode 9.

  The dielectric component in the present invention is not limited to the case where it is used like a capacitor, and widely means a component having a dielectric property. Therefore, when the dielectric 6 having a piezoelectric characteristic such as PZT is used, in addition to the usage as a capacitor, it can be used as an inertial force sensor such as an angular velocity sensor or an acceleration sensor, or as an actuator. Although it can be used, the dielectric component according to the present invention includes such a dielectric component.

  In Embodiment 1, the insulating layer 2, the first adhesion layer 3, and the orientation control layer 5 are formed. However, one of these, or a configuration that does not include these two or more elements. It can also be. However, it is preferable that these are formed for the reasons already described.

  As described above, the dielectric component according to the present invention includes the substrate 1, the lower electrode 4 formed on the upper surface side of the substrate 1, and the dielectric containing oxygen atoms formed on the upper surface side of the lower electrode 4. Body 6, diffusion prevention layer 7 formed on the upper surface side of dielectric 6, and second layer formed directly on the upper surface of diffusion prevention layer 7 or directly on the upper surface of diffusion prevention layer 7. An upper electrode 9 formed on the upper surface side of the adhesion layer 8, and the diffusion prevention layer 7 is stable with respect to the dielectric 6. With this configuration, the diffusion prevention layer 7 6 is stable with respect to 6, so that the oxygen atoms contained in the dielectric 6 are not deprived, whereby oxygen atoms are not lost in the dielectric 6, and the deterioration of characteristics can be prevented. Has an effect.

  In the dielectric component according to the present invention, the diffusion prevention layer 7 is stable with respect to the upper electrode 9 or the second adhesion layer 8 directly formed on the upper surface thereof. The layer 7 does not chemically react with the upper electrode 9 or the second adhesion layer 8 formed directly on the upper surface thereof, and thus the diffusion prevention layer 7 is stable with respect to the dielectric 6. Therefore, the oxygen atoms contained in the dielectric 6 are not deprived. As a result, the dielectric 6 has an effect of preventing oxygen atoms from being lost and preventing deterioration of characteristics.

  In addition, in the dielectric component of the present invention, the diffusion prevention layer 7 is made of an oxide. According to this structure, the diffusion prevention layer 7 itself has already been oxidized, so oxygen in the dielectric 6 Without taking away the atoms, it is possible to prevent the loss of oxygen atoms constituting the dielectric 6 and to prevent the deterioration of the characteristics.

  Furthermore, in the dielectric component of the present invention, the diffusion prevention layer 7 is made of nitride, and according to this configuration, the diffusion prevention layer 7 is formed of nitride, which is a stable substance. The anti-diffusion layer 7 does not take away oxygen atoms constituting the dielectric 6, thereby preventing defects of the oxygen atoms constituting the dielectric 6 and preventing the deterioration of characteristics. Play.

Furthermore, in the dielectric component of the present invention, the diffusion prevention layer 7 is made of one or more substances selected from SiO ₂ , SiN, SiON, BaTiO ₃ and SrTiO ₃ , and according to this configuration, Since the diffusion prevention layer 7 is formed of a material more stable than the dielectric 6, the diffusion prevention layer 7 does not deprive the oxygen atoms constituting the dielectric 6, and thus the oxygen atoms constituting the dielectric 6 are deficient. It is possible to prevent the deterioration of characteristics and the effect of being able to prevent deterioration of characteristics.

(Embodiment 2)
Hereinafter, the inventions of the present invention will be described with reference to the drawings.

  FIG. 2 is a front sectional view of a dielectric component according to Embodiment 2 of the present invention. The dielectric component according to the second embodiment has a configuration in which the diffusion preventing layer 7 of the dielectric component according to the first embodiment covers the side surface of the dielectric 6 and the side surface of the lower electrode 4 and extends to the substrate 1. . Moreover, the composition of the substrate 1, the insulating layer 2, the first adhesion layer 3, the lower electrode 4, the orientation control layer 5, the dielectric 6, the diffusion prevention layer 7, the second adhesion layer 8 and the upper electrode 9 is respectively implemented. The same dielectric component as in the first embodiment can be used.

By adopting such a configuration, in addition to the function and effect of the dielectric component according to the first embodiment, the dielectric 6 can be protected from the atmosphere around the dielectric component by covering the side surface of the dielectric 6 as well. . For example, oxygen atoms can be prevented from leaving the dielectric 6 even in a reducing atmosphere. The diffusion prevention layer 7 is configured to cover the dielectric 6, but is not configured to cover the second adhesion layer 8. For this reason, when the dielectric component according to the present embodiment is in an atmosphere in which oxygen is present, Ti constituting the second adhesion layer 8 takes in oxygen in the air to become TiO ₂ , and is combined with oxygen in the air. Since it reacts to become an oxide, oxygen atoms are not taken away from the diffusion preventing layer 7 and the dielectric 6, and deterioration of characteristics as a piezoelectric component can be efficiently prevented.

  As described above, in the dielectric component according to the second embodiment of the present invention, the diffusion prevention layer 7 extends from the upper surface of the dielectric 6 to the side surface of the dielectric 6 and the side surface of the lower electrode 4 and extends to the substrate 1. Since the side surface of the dielectric 6 is also covered with the diffusion preventing layer 7, it is possible to prevent oxygen atoms in the dielectric 6 from being lost even if the environment where the dielectric component is placed is a reducing atmosphere. Since the diffusion prevention layer 7 does not cover the side surface of the second adhesion layer 8, the second adhesion layer 8 can deprive the atmosphere of oxygen, and by this oxidation, oxygen atoms of the dielectric 6 can be obtained. The loss of oxygen atoms in the dielectric 6 can be prevented more stably, and the deterioration of characteristics can be prevented.

  The dielectric component in the second embodiment also has the same effect as the dielectric component in the first embodiment, and can be further developed in the same manner as the dielectric component in the first embodiment. For example, it is possible to eliminate the second adhesion layer 8 of the dielectric component in the second embodiment and form the upper electrode 9 directly on the diffusion prevention layer 7.

  The dielectric component according to the present invention has an effect of preventing deterioration of characteristics, and is useful when applied to various sensors such as a capacitor, an angular velocity sensor, and an angular velocity sensor.

Front sectional view of dielectric component according to Embodiment 1 of the present invention Front sectional view of a dielectric component according to Embodiment 2 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Insulating layer 3 1st adhesion layer 4 Lower electrode 5 Orientation control layer 6 Dielectric 7 Diffusion prevention layer 8 2nd adhesion layer 9 Upper electrode

Claims (6)

A substrate, a lower electrode formed on the upper surface side of the substrate, a dielectric containing oxygen atoms formed on the upper surface side of the lower electrode, a diffusion prevention layer formed on the upper surface side of the dielectric, An upper electrode formed directly on the upper surface of the diffusion prevention layer or formed on the upper surface side of the intermediate layer formed directly on the upper surface of the diffusion prevention layer, and the diffusion prevention layer is disposed on the dielectric. Dielectric parts that are stable and stable. The dielectric component according to claim 1, wherein the diffusion preventing layer extends from the upper surface of the dielectric to the substrate covering the side surface of the dielectric and the side surface of the lower electrode. 3. The dielectric component according to claim 1, wherein the diffusion preventing layer is stable with respect to the upper electrode or intermediate layer directly formed on the upper surface thereof. The dielectric component according to claim 1, wherein the diffusion prevention layer is made of an oxide. The dielectric component according to claim 1, wherein the diffusion prevention layer is made of nitride. _3. The dielectric component according to claim 1, wherein the diffusion prevention layer is made of one or more substances selected from SiO ₂ , SiN, SiON, BATiO ₃ and SrTiO ₃ .

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